The devices currently known are of the type comprising:                a movable conveyor having:                    a plurality of container supports distributed along the conveyor;            a plurality of nozzles for injecting fluid into the containers, each one mounted facing a respective container support;            a nozzle fluid-feed track, arranged along the conveyor, and            a plurality of pipes for conveying fluid to the nozzles, each one connected to a respective nozzle and having an inlet arranged in the feed track, the inlets being distributed along the feed track, and                        a fixed fluid dispenser alongside the conveyor, designed to introduce fluid successively into the inlets, this dispenser comprising:                    a distributor positioned facing the feed track and designed to cover a number N of inlets selected at the time of the relative displacement of the feed track in relation to the distributor, and            means to feed the distributor with fluid.                        
In such a known device, the conveyor is a carousel and the track forms a central hub into which the distributor extends, in the form of a fixed shaft.
The distributor and the track delimit between them a circumferential groove fed with fluid by the distributor. An obstruction seal is fixed to the distributor inside the groove, through an are of a preset length so as to obstruct a given number of inlets. Thus, the distributor covers and supplies with gas those inlets which are not obstructed by the obstruction seal.
Circular seals are mounted above and below the groove, between the distributor and the carousel.
In order to ensure that the seals provide a good seal, it is necessary to ensure a relative rotary movement between the conveyor and the distributor that is as accurate as possible. Thus, the carousel is mounted rotating in relation to the distributor by means of two bearings, for example ball-bearings, arranged on either side of the groove. These bearings are located as far as possible from one another along the axis of rotation so that no radial clearance is possible.
A consequence of this constraint is that the known device occupies considerable space along the axis of rotation and moreover uses rollers that must operate at a high temperature, which makes them costly.